Concave water ski



March 16, 1965 M. G. AMSBRY 3,173,161

CONCAVE WATER SKI I Filed Sept. 10, 1965' 2 Sheets-Sheet 1 INVENTOR.

BY WPLW 7 2 2 FIG.3 FIG. 4 ATTORNEYS MICHAEL G. 'AMSBRY United StatesPatent 3,173,161 CONCAVE WATER SKI Michael G. Amshry, Orange, Calif.(2712 Laurel St., Napa, Calif.) Filed Sept. 10, 1963, Ser. No. 308,021 3Claims. (Cl. 9-310) This invention relates to water skis and moreparticularly to a new slalom ski for water skiing.

In the sport of water skiing, the skills of the skier findv theirgreatest test in competitive slalom skiing where the skier must exercisesubstantially perfect balance and control. Success in competitive slalomskiing is dependent first and foremost on the development of theseskills, but substantial benefit can be obtained from the use of aproperly designed slalom ski.

In the course of a substantial amount of competitive water skiing inrecent years, I have developed a slalom ski which appears to have thebest physical characteristics of the ski for providing the skier withmaximum stability of the ski and maximum control in the sense ofproviding a ski which responds very rapidly to actions of the skier inattempting to change direction. This design is the combination ofseveral years of testing of a number of ditferent prototypes and the skiof this design appears to me to offer better stability and control thanany other of the prototypes or any of the various skis which areavailable commercially.

The design of this ski is illustrated in the attached drawings which areto scale, in which:

FIG. 1 is a perspective view of the ski;

FIG. 2 is a plan view on a larger scale;

FIG. 3 is a view in side elevation of the ski;

FIG. 4 is a view in longitudinal section of the ski, and

FIGS. 5-11 are cross sectional views of the ski taken along the planesindicated at the corresponding positions in FIG. 2.

The most important features of the ski are its profile, that is itsshape seen in FIG. 2, its concave bottom, and its laminated structurewhich give to the ski somewhat more than moderate flexibility Whileproviding substantial strength in the ski in all areas of the skiregardless of concavity.

Referring now in detail to the drawings, the ski has an elongated bodywhich consists essentially of eight elongated laminations 11 of ahardwood such as Ash which are bonded together in side by side relationby a conventional water resistant cement. The ski has an upturnedforward tip portion 12 and an elongated running portion which joins thetip portion at an imaginary transverse line 13, a top surface having aski boot support area 14 on which may be mounted a conventional bindingfor receiving the skiers foot, a rearward step area 16 and a tail fin18. The step area 16 is defined by a cork pad, and any suitableauxiliary binding may be provided on the step area if desired,

The lower surface of the ski is provided with an elongated concavesurface 20 which extends from the transverse line 13 to the rearward endof the ski, with the bottom surface 22 forward of the transverse line 13being generally flat. The concave running surface 20 is bounded bycurved edges 24, and the forward flat surface portion 22 is bounded bysharp edges 26.

The running portion of the ski, that is below the transverse line 13 inFIG. 2 is generally straight from the transverse line 13 toapproximately the mid-point of the step area 16 as indicated at 28 inFIGS. 3 and 4, and the rearward portion of the ski below the arrows 28in FIGS. 3 and 4 is bent upwardly through an angle of between one andfive degrees toward the same side of the straight running portion as theupcurved tip 12. This small in- 3,173,161 Patented Mar. 16, 1965clination at the rear of the ski provides an effective rocker by whichthe planing angle of the ski in the water may be controlled veryeffectively with shifting of the skiers weight.

The concave surface 20 on a ski of the profile illus trated in thedrawing provides the best design I have yet tested for imparting to theski the best characteristics of stability and control. The concavesurface should have a radius of curvature substantially constant alongthe length of the ski and between about two and five times the maximumwidth of the ski. In this regard, the ski illustrated in the drawing hasa length of approximately 67 inches, a maximum width located between theplanes of FIGS. 8 and 7 of about 6.5 inches, a maximum thickness of A ofan inch, and approximately a 15 inch radius of curvature for the concavesurface 20. The radius of curvature of the curved edges 24 isapproximately of an inch, and the angle change of the running portion ofthe ski at 28 is approximately two degrees. The ski having thesedimensions has been found to provide best performance.

The ski is moderately flexible, and the side by side arrangement oflaminae 11 provides excellent control of this flexibility and strengthin the ski where the thicknesses of the laminae change in the area ofthe concave surface 20.

In some instances, it may be desirable to provide a somewhat modifiedshape on the tail end of the ski since some skiers prefer a flared fishtail profile, but I have found that the converging profile illustratedin the drawing is most satisfactory for most skiing conditions. It mayalso be desirable in some situations to provide the ski with an exteriorcoating of polyester resin impregnated in glass fibers either to controlthe flexibility of the ski or strengthen its surface against wear, butgenerally speaking I prefer not to employ such a covering. In the skiillustrated in the drawing, there is however provided an epoxy coatingon the top of the ski which because of its thickness does not show onthe drawings, this coating being provided for wear and decorativepurposes,

While one specific embodiment of the invention has been illustrated anddescribed herein, this is but the best Way I contemplate of carrying outthe invention, and certain modifications in the ski design may be madewithout departing from the spirit and scope of the invention.

I claim:

1. A slalom water ski comprising an elongated ski body having a rearwardend, an elongated running portion, and a forward upcurved tip portionintegrally formed with said running portion and joining said runningportion along a line extending transversely of said body, said bodyhaving a lower water engaging surface and an upper support surfacedefining the plan profile of said body with said body consistingessentially of a plurality of laminae of hardwood extending along thelength of the body and positioned in side by side relation to each otherand imparting to said body substantial longitudinal flexibility, a skiboot support area on said upper support surface positioned atapproximately the mid-point of the length of said running portion, and astep area on the upper support surface between said ski boot supportarea and said rearward end, said plan profile being smoothly taperedthroughout the length of said body with its area of maximum widthlocated between said ski boot support area and said transverse line andwith said profile decreasing in width continuously from said area ofmaximum width to a position between said step area and said rearwardend, the transverse cross section of said lower water engaging surfacehaving a flat shape forward of said transverse line and a concave shapeextending substantially the full width of said running portion to therear 'of said transverse line where the radius of curvature of saidconcave shape is substantially constant along the entire length of saidrunning portion and is between about two and five times the maximumwidth of said body.

2. A water ski according to claim 1 wherein said lower water engagingsurface is defined by the lower surfaces of said laminae.

-3. A slalom water ski comprising an elongated ski body having a lengthof about 67 inches, a thickness of about /8 of an inch, an elongatedrunning portion about 55 inches long and a forward upcurved tip portionabout 12 inches long integrally formed with said running portion andjoining said running portion along a line extending transversely of saidbody, said body having a lower water engaging surface and an upper flatsupport surface defining'the plan profile of said body, a ski bootsupport area on said upper support surface positioned at approximatelythe mid-point of the length of said runof maximum width of about 6.5inches located about midway between said ski boot support area and saidtransverse line, and with said profile decreasing in width continuouslyfrom said area of maximum width to a width of about 2 /2 inches adjacentto the end of said ski remote from said tip portion, and the transversecross sections of said lower water engaging surface having a flat shapewith sharp edges forward of said transverse line and a concave shapeextending the full width of the ski with rounded edges to the rear ofsaid transverse line where the radius of curvature of said concaveshapeis substantially constant at about 15 inches along the entire length ofsaid running portion and where the radius of curvature of said roundededges is substantially constant at about 0.2 inches along the length of,said running portion.

' References Cited in the file of this patent UNITED STATES PATENTSAbbott et a1, Oct. 2, 1962

1. A SLALOM WATER SKI COMPRISING AN ELONGATED SKI BODY HAVING A REARWARDEND, AN ELONGATED RUNNING PORTION, AND A FORWARD UPCURVED TIP PORTIONINTEGRALLY FORMED WITH SAID RUNNING PORITON AND JOINING SAID RUNNINGPORTION ALONG A LINE EXTENDING TRANSVERSELY OF SAID BODY, SAID BODYHAVING A LOWER WATER ENGAGING SURFACE AND AN UPPER SUPPORT SURFACEDEFINING THE PLAN PROFILE OF SAID BODY WITH SAID BODY CONSISTINGESSENTIALLY OF A PLURALITY OF LAMINAE OF HARDWOOD EXTENDING ALONG THELENGTH OF THE BODY AND POSITIONED IN SIDE BY SIDE RELATION TO EACH OTHERAND IMPARTING TO SAID BODY SUBSTANTIAL LONGITUDINAL FLEXIBILITY, A SKIBOOT SUPPORT AREA ON SAID UPPER SUPPORT SURFACE POSITIONED ATAPPROXIMATELY THE MID-POINT OF THE LENGTH OF SAID RUNNING PORTION, AND ASTEP AREA ON THE UPPER SUPPORT SURFACE BETWEEN SAID SKI BOOT SUPPORTAREA AND SAID REARWARD END, SAID PLAN PROFILE BEING SMOOTHLY TAPEREDTHROUGHOUT THE LENGTH OF SAID BODY WITH ITS AREA OF MAXIMUM WIDTHLOCATED BETWEEN SAID SKI BOOT SUPPORT AREA AND SAID TRANSVERSE LINE ANDWITH SAID PROFILE DECREASING IN WIDTH CONTINUOUSLY FROM SAID AREA OFMAXIMUM WIDTH TO A POSITION BETWEEN SAID STEP AREA AND SAID REARWARDEND, THE TRANSVERSE CROSS SECTION OF SAID LOWER WATER ENGAGING SURFACEHAVING A FLAT SHAPE FORWARD OF SAID TRANSVERSE LINE AND A CONCAVE SHAPEDEXTENDING SUBSTANTIALLY THE FULL WIDTH OF SAID RUNNING PORTION OF THEREAR OF SAID TRANSVERSE LINE WHERE THE RADIUS OF CURVATURE OF SAIDCONCAVE SHAPE IS SUBSTANTIALLY CONSTANT ALONG THE ENTIRE LENGTH OF SAIDRUNNING PORTION AND IS BETWEEN ABOUT TWO AND FIVE TIMES THE MAXIMUMWIDTH OF SAID BODY.